This grant application is initiated by Ion Channel Innovations, LLC., (ICI) an early stage biotechnology company that has completed the first, and only, phase I safety trial using plasmid DNA transfer with a non-specific gene MaxiK potassium channel promoter to treat urinary urgency, frequency, nocturia, and incontinence also known as overactive bladder or OAB a disease that affect 17 million persons in the US. There were no gene transfer related serious adverse events in either the short or long term follow-up of that trial. The goal of this application is to potentially improve the efficacy of the company's product. The hypothesis of this grant is whether or not a cell-specific promoter of the maxi-K gene alone, or in combination with another cell specific promoter, better reduce or prevent bladder smooth muscle overactivity than does a non-specific CMV promoter of the MaxiK channel. To test that hypothesis the grant has two specific aims. In Specific Aim 1 a vector will be constructed in which the gene for the MaxiK potassium channel (hSlo) will be expressed from a urothelial cell specific promoter. That promoter that will be compared in a variety of cell types (tissue cultured rat urothelium, rat bladder smooth muscle, and HEK cells) to cell type specific expression of hSlo from two other well characterized constructs (expressing hSlo from a non-cell-type specific promoter (CMV) and a smooth muscle specific promoter (SMAA). Specific Aim 2 will determine which specific promoter driving hSlo expression best reverses bladder smooth muscle hyperactivity in an in vivo animal model of OAB using standard urodynamic parameters. The expected results are that the urothelial specific promoter alone or in combination with the smooth muscle promoter will be significantly more effective in reducing bladder smooth muscle overactivity when compared to use of the non-specific CMV promoter. If the hypothesis is proved correct with statistical evidence that one or more specific promoters of the MaxiK gene better treats the symptoms of OAB the company will extend its patent portfolio, begin commercial production of the product, and immediately use the product in IND approved trials. The development of a safe and effective long lasting therapy for OAB will be a major medical advance.